Electric cable pothead



May 16, 1933.

G. A. MATTHEWS ELECTRIC CABLE POTHEAD Filed Feb. 24, 1930 Patented May 16, 1933 UNITED STATES PATENT OFFICE GEORGE A. MATTHEWS, 01 DETROIT, MICHIGAN ELECTRIC CABLE POTHEAD 'Application filed February 24, 1930. Serial No. 430,780.

This invention relates to means for protectbushing for all connector parts and to so ing high potential systems when changing provide for the replacement of any broken from one medium to another, and particularbushing without disturbing any of the 1y to the special type of devices known as potothers.

heads. A still further object is to provide a base It is the object of this invention to provide opening in the pothead body to facilitate the an improved medium in which conductors training of conductors and to allow inspeccarrying a high voltage may be safely spaced tion of the cable crotch at the point of enwhen discontinuing insulation such as is used trance.

10 for underground cables in changing to the linother object is to provide a clamping spacing required for aerial conductors. flange over the end of the cable sheathing to It is a more specific object of the invention effect an oil tight union with the lead sheath to provide a pothead in which oil may be used Within the cable conduit, the clamping flange as an insulating medium, and to provide a to be provlded with a lead ring soldered into 15 structure which will be of minimum size and a tinned groove to which the cable sheath may reduced weight so that the quantity of oil rebe soldered, quired will, consequently, be a minimum. @ther ob]ects are to provide a pothead hav- It is a further object to provide a pothead 111g neat body lines in order to harmonize with which is adaptable for connection with a reany well designed installation, to provide a 0 motely located oil reservoir and which will structure which will readily lend itself to retain a suflicient amount of oil therein for installation by a mechanic using ordinary safe operation in case of leakage or a break care and ordlnary tools and not requiring i th il fi fr m th s rv ir, wiped joints and like operations.

It is a further object of the invention to It is still another object to design a pot- 25 provide an efficient moisture seal for the ends head in such a way that bushing type current of the cables, this moisture seal also acting to transformers can be installed over the tubes retain oil in the pothead. enclosing the individual conductors.

It is a still further object to provide a pot- Other objects and advantages will become head through which the cable conductors may apparent as reference is had to the accom- 30 be carried with a minimum of bending so that panying drawing wherein is illustrated, by the insulation thereon may not be damaged as way of example only, one embodiment of my by cracking or creasing. invention and in which:

It is a further object to provide suitable The figure is aside elevation,partly broken supports for the conductors which may be enaway for purposes of explanation, of my 35 tirely capable of withstanding the longitudiimproved pothead. nal and tangential stresses to which they may Referring more particularly to the drawbe subjected. It is well known that a wire ing, numeral 1 designates my improved potcarrying a high voltage, when short-cirhead as a whole which is composed of a potcuited, exerts an enormous force tending to head body 2 having conductor housings 3 0 straighten itself so that the supports just reradiating therefrom in the form of tubing to ferred to will be understood to cooperate with each of which is attached at the end thereof the object above named, having the conduca porcelain bushing 42 by means of a collar 5 tor assume a substantially straight course which is secured to tubing 8 by bolts 6 and through the pothead. It is to be noted that secured against leakage by washers 7. The this characteristic of a high potential wire bushing s carries at its outer end an open has, heretofore, presented one of the greatest ended cap 8 having upwardly converging problems in the construction of potheads, and sides through which a plug 9 extends, the has been a continuous source of trouble in purpose of which will hereinafter become conventional potheads. apparent. Over the end of cap 8 is placed It is a further object to provide a porcelain a washer 10 against which rests a bell cap 11 having an opening 12 in the outer end thereof for reception of a conductor through which current may be taken from the pothead. The bell portion of cap 11 houses the plug 9 and acts to restrain moisture from contacting the washer 10 and thence finding its way into tubing 3.

Interiorly of cap 11 is fitted, preferably by screwing, a bolt 13 having a cap 14 as its head. The cap 14 acts as a connector receiving in a soldered joint the end of a conductor 15.

A cable 16 containing a plurality of conductors, illustrated as being three in number and designated, 17, 18 and 19, is of conventional type with conventional insulation and conventional lead sheathing such as is used in leading conductors underground. Upon changing from the insulation commonly used for underground conductors to aerial conductors, it is necessary to space the individual conductors comprising the cable so that an air gap of suflicient size to replace the insulation may be had. In spreading the individual conductors, each branch is led through an individual tube 3, then bushing 4 and is reduced in size to form what has been described as a smaller conductor 15 for cooperation with connector 14.

In order that proper insulation may be provided for the individual conductors at the point of spread and vicinity, the pothead body 2 is hollowed out somewhat as shown in the drawing whereby it may contain a suitable amount of insulation which I provide in the form of oil. For the purpose of supplying oil to the body 2 there is a pipe line 30 leading from any suitable source of supply, not shown, to any desired point in the pothead. When providing a line from a remote point, leakage or breakage is liable to occur so that I connect pipe 17 into the top of one of tubes 3. Thus, if breakage or leakage occurs, the oil level in the pothead may not fall below the level of the point of entrance and the body 2 is guaranteed of containing a sufiicient supply to guarantee safe operation.

In leading the conductors through the pothead body, it is desirable to lead them with a minimum of bending for two reasons, first, the insulation on the conductors is less likely to crack or crease and, secondly, an enormous force is exerted by the conductor to straighten itself in case of a short-circuit anywhere along the line. In order to provide direct supporting means for preventing straightening of the conductor, I provide an insulated sheath 31 within each tube 3 in spaced relation with the sides. A conical metallic collar 32 is securely mounted on each conductor at the end of the sheath so that the force exerted at the point of bend will be directly assumed by the sheath and the connection at the connector 14 free from danger of being pulled loose.

The tubes containing the conductors diverge from the body 2 and are braced in spaced relation by supports 33.

The base of body 2 is formed in such a way as to be suited for mounting directly on the cable. Thus a collar 20 may fit around the cable prior to entering the pothead. The lead sheath of the cable 16 is flared outwardly to conform to the shape of a flared portion 21. Embedded in the portion 21 is a lead ring 22 which may be soldered to portion 21 and also to the flared lead sheathing. On top of the portion 21 is a washer 23. The pothead base is of conformation to fit the collar 20 while resting on the washer 23 so that as the collar and pothead are drawn together by means of bolts 24 the washer 23 and lead ring 22 form a very eflicient seal to retain the oil and to keep out moisture.

A plate 25 is provided, as shown, in order to allow of training the conductors through their respective tubes, to permit of inspection at the pothead crotch and to permit of cleaning when desired.

After plates 25 have been secured bolted in place, plugs 9 are removed from each tube and oil may then be fed into the pothead through pipe 30 from the source of supply. As soon as oil overflows and runs out of the plug openings, the plugs are then replaced.

am aware that numerous details of construction may be varied through a wide range without departing from the principles of this invention, and I therefore do not purpose limiting the patent granted, otherwise than necessitated by the prior art.

I claim as my invention:

1. In a pothead, the combination of a pothead body arranged for securing to a supporting structure, an elongated metallic tubular member for forming a cable housin and having one end ri idly secured to said Iiody, a bushing secured at the other end of said member spaced from said body and having a terminal connection at its outer end, an insulated cable extending into said body, through said member and bushing where it is connected to said terminal, a sheath of insulating material surrounding said cable, and means adjacent the ends of said member for supporting and centering said sheath within said housing.

2. In a pothead, the combination of a pothead body arranged for securing to a supporting structure, a plurality of elon ated metallic tubular members secured to said ody so as to diverge outwardly therefrom and form individual cable housings, bushings secured respectively at the outer ends of said members having terminal connectors, means for bringing a multi-conductor cable into said body adjacent the inner ends of said members, the conductors of said cable being indi- Vidually carried through said body, members and bushings, and secured to said terminals, sheaths of insulating material surrounding the cables Within the housings, means adjacent the ends of said tubular members for supporting and centering said sheaths Within the housings, said sheaths being extended past their inner supports into said body for supporting the conductors between the cable and tubular members.

In testimony whereof I have hereunto subscribed my name at Detroit, Wayne County,

Michigan.

GEORGE A. MATTHEWS. 

